1. Field of the Invention
The present invention relates to methods for manufacturing active fixation electrodes for electrical medical leads, in particularly helix electrodes intended to be screwed into body tissue.
2. Description of the Prior Art
Implantable medical electrical stimulation and/or sensing leads (also called “leads” or “electrode leads”) are well known in the fields of tissue and organ stimulation and monitoring. Such fields include cardiac pacing. Leads may be attached to an organ by an active fixation means which is designed to penetrate the surface of the organ that is to be stimulated or sensed. A common active fixation means employs a helix which has a sharpened tip and is mounted at the end of the electrode lead. The fixation helix typically has an outside helix diameter which is slightly less than that of the lead body and extends in axial alignment with the lead body. The sharpened tip of the helix can be screwed into the organ by being rotated. Typically the helix is electrically connected to one or more conductors in the electrode lead. These conductors can be electrically connected to one or more exposed surfaces of the helix which then can be used as stimulating and/or sensing electrodes. A fixation helix therefore may contain one or a plurality of conductors. Typically the outer surface of the helix, including the exposed surfaces used as electrodes, is partly covered with a biocompatible coating to minimize interference with the tissue to which it is to be attached. Typically the biocompatible coating is electrically conducting and it is arranged in a predetermined pattern with continuous gaps on the insulating material und the exposed electrode surfaces in order to prevent the different electrodes from being in electrical contact with each other. The sizes of the surface areas of the exposed electrodes are set at levels which are compatible with the organ they are attached to United States Patent Application Publication 2006/0122682 describes an active fixation helix for an electrical medical leads and methods of making such active fixation helixes.